Larger Increase In Heart Rate Research Articles

High-intensity interval training (HIIT) and slow breathing interventions alleviate premature ejaculation (PE) symptoms

BackgroundPhysical exercise may alleviate premature ejaculation symptoms, a prevalent male sexual dysfunction linked to a series of negative outcomes for men and their partners. ObjectiveWe investigated the effectiveness of high-intensity interval training (HIIT) and slow breathing interventions on premature ejaculation symptoms and their relation to autonomic activity and attention regulation. MethodChinese adult men (N = 76, M = 21.89, SD = 3.32) with premature ejaculation completed one of the two-week interventions in their homes or as participants in a normal breathing control group; they reported their age, height, weight, physical activity level, premature ejaculation symptoms, and attention regulation. In the HIIT group, 26 participants engaged in a 7-minute HIIT each day. In the slow breathing group, 25 participants performed 7-minute slow breathing exercises per day while the 25 participants in the normal breathing group similarly performed normal breathing exercises. All participants measured their heart rate once before and five times (with one-minute intervals) after the intervention. When participants had penile-vaginal sex with their partners, they measured their heart rate once after ejaculation. ResultsTime × Intervention interaction was significant with lower levels of premature ejaculation symptoms on Days 12, 13, and 14 in the HIIT group (M ± SD = 16.19 ± 3.45, 15.96 ± 3.43, and 15.15 ± 3.62) compared to the normal breathing group (M ± SD = 17.68 ± 3.06, 17.68 ± 3.15, and 17.44 ± 3.25). Higher levels of attention regulation were associated with fewer premature ejaculation symptoms. We also found that a larger increase in heart rate from resting to after sex was associated with fewer premature ejaculation symptoms. ConclusionCompared to the control group, the efficacy of two weeks of HIIT exercise in mitigating PE symptoms suggests its potential as a novel treatment for PE.

Cardiorhythm in postural changes depending on the autonomic centers reactivity

Postural changes are accompanied by the formation of an adaptive response of the cardiovascular system. This is manifested by a change in heart rate variability. The features of the reaction largely depend on the excitability (reactivity) of the vegetative centers. The aim of the study was to identify individual features of heart rate regulation in postural changes depending on the reactivity of sympathetic and parasympathetic autonomic centers in students. Material and Methods. In 50 men, temporal, frequency, geometric and calculated indicators of heart rate variability were determined in a horizontal position, with active orthostasis, passive orthostasis and passive antiorthostasis. The reactivity of the sympathetic system was assessed by the change of heart rate in active orthostasis. The reactivity of the parasympathetic system was determined by K30:15. Results and Discussion. With normal and high sympathetic reactivity, active orthostasis causes an increase in the low-frequency power of the spectrum, stress index, heart rate, a decrease in the high-frequency component and the duration of cardiac intervals. The changes are more pronounced with high sympathetic reactivity. In passive orthostasis, high sympathetic reactivity is manifested by a large increase in heart rate, shortening of cardiac intervals and a decrease in the proportion of the spectrogram high-frequency component. Passive antiorthostasis with normal sympathetic reactivity causes a decrease in the adequacy of the regulation processes and an expansion of the scatterogram. In subjects with high parasympathetic reactivity with active orthostasis, the increase in the stress index is less than with normal and low reactivity. With low parasympathetic reactivity, the indicator of the adequacy of the regulation processes is greater than with normal and high reactivity, and the increase in heart rate and shortening of the minimum cardiac interval is greater than with normal. In passive orthostasis, the proportion of the high-frequency component decreases, the proportion of the ultra-low-frequency component increases, the modal cardiointerval shortens, which is more pronounced with low parasympathetic reactivity than with normal. In passive antiorthostasis, the ultra-low frequency component decreases in individuals with normal reactivity. With high reactivity, the maximum value of the high-frequency component increases and the adequacy of the regulation processes decreases. Conclusion. Active and passive orthostasis is accompanied by activation of sympathetic centers. It is more pronounced with high reactivity of the sympathetic department and low reactivity of the parasympathetic. Passive antiorthostasis stimulates the activity of parasympathetic cardiac centers in subjects with normal, high parasympathetic reactivity and normal sympathetic reactivity.

Acute work rate adjustments during high-intensity interval training in a hot and temperate environment.

Heart rate drifts upward over time during interval exercise and during exercise in hot conditions. As such, work rate must be lowered to maintain target heart rate. The purpose was to characterize acute work rate adjustments during high-intensity interval training based on target heart rate. Seven humans (three females) completed five study visits: a graded exercise test on a cycle ergometer to measure maximal heart rate (HRmax) in ∼22°C and four trials performed in ∼22°C (TEMP) or ∼35°C (HOT), consisting of an 8 min warm-up at 70% HRmax followed by one (15TEMP and 15HOT) or five (43TEMP and 43HOT) rounds of high-intensity interval training (one round = 4min work at 90% HRmax and 3min recovery at 70% HRmax) totaling 15min or 43min of exercise, respectively. Work rate was lowered 33 ± 20W (p=0.005) in 43TEMP and 56 ± 30W (p=0.003) in 43HOT between the first and fifth work intervals. Thermal strain (0.2°C higher rectal temperature, p=0.01) and cardiovascular strain (6 beats·min-1 larger increase in heart rate from first to fifth recovery interval, p=0.01) were greater in 43HOT versus 43TEMP. Using target heart rate during high-intensity interval training may reduce the training stimulus, especially in hot environments, but it may also limit thermal strain and enable participants to complete the prescribed workout despite the heat.

Cardiopulmonary and cerebrovascular acclimatization in children and adults at 3800m.

Maturational differences exist in cardiopulmonary and cerebrovascular function at sea-level, but the impact of maturation on acclimatization responses to high altitude is unknown. Ten children (9.8±2.5years) and 10 adults (34.7±7.1years) were assessed at sea-level (BL), 3000m and twice over 4days at 3800m (B1, B4). Measurements included minute ventilation ( ), end-tidal partial pressures of oxygen ( ) and carbon dioxide, echocardiographic assessment of pulmonary artery systolic pressure (PASP) and stroke volume (SV) and ultrasound assessment of blood flow through the internal carotid and vertebral arteries was performed to calculate global cerebral blood flow (gCBF). At 3000m, was increased from BL by 19.6±19.1% (P=0.031) in children, but not in adults (P=0.835); SV was reduced in children (-11±13%, P=0.020) but not adults (P=0.827), which was compensated for by a larger increase in heart rate in children (+26 beatsmin-1 vs. +13 beatsmin-1 , P=0.019). Between B1 and B4, adults increased by 38.5±34.7% (P=0.006), while did not increase further in children. The rise in PASP was not different between groups; however, ∆PASP from BL was related to ∆ in adults (R2 =0.288, P=0.022), but not children. At BL, gCBF was 43% higher in children than adults (P=0.017), and this difference was maintained at high altitude, with a similar pattern and magnitude of change in gCBF between groups (P=0.845). Despite increasing in children but not adults at a lower altitude, the pulmonary vascular and cerebrovascular responses to prolonged hypoxia are similar between children and adults. KEY POINTS: Children have different ventilatory and metabolic requirements from adults, which may present differently in the pulmonary and cerebral vasculature upon ascent to high altitude. Children (ages 7-14) and adults (ages 23-44) were brought from sea level to high altitude (3000 to 3800m) and changes in ventilation, pulmonary artery systolic pressure (PASP) and cerebral blood flow (CBF) were assessed over 1 week. Significant increases in ventilation and decreases in left ventricle stroke volume were observed at a lower altitude in children than adults. PASP and CBF increased by a similar relative amount between children and adults at 3800m. These results help us better understand age-related differences in compensatory responses to prolonged hypoxia in children, despite similar changes in pulmonary artery pressure and CBF between children and adults.

Changes in acceleration load as measured by inertial measurement units manifest in the upper body after an extended running task

ABSTRACT The purpose of this study was to investigate the behaviour of physiological load measures as well as ground reaction forces (GRF) and acceleration load during a prolonged running task that simulated the running demands of an intermittent team sport. Nineteen males completed a maximal aerobic fitness test and an extended running protocol across two sessions. Participants wore a portable metabolic system, and four inertial measurement units (IMU), one on each foot, the lower back and upper back. GRF were measured via an instrumented treadmill. Change in metabolic, IMU and GRF variables across five blocks during the running protocol were assessed using a one-way repeated measures ANOVA. The running protocol elicited large increases in heart rate and oxygen consumption over time. No statistically significant changes in any peak impact accelerations were observed. Resultant acceleration area under the curve (AUC) increased at the lower and upper back locations but was unchanged at the foot. GRF active peak but not impact peak increased during the prolonged run. The results of this study indicate that the effect of an extended running task on IMU measures of external mechanical load is manifested in the upper body, and is effectively measured by AUC.

Sustained hypoxia in mice increases parasympathetic but not sympathetic tone.

The autonomic profile of mice submitted to sustained hypoxia (SH) was not yet fully evaluated. Herein, we characterized the cardiovascular and autonomic profile of conscious freely moving mice submitted to SH using two sequential experimental protocols to evaluate the parasympathetic and sympathetic tone to the heart and the sympathetic tone to the vascular resistance. In the first protocol the sequence of antagonists was methyl-atropine followed by propranolol and then by prazosin, while in the second protocol the sequence was propranolol followed by methyl-atropine and then by prazosin. In SH the baseline heart rate was significantly lower than in control mice and the antagonism of the parasympathetic and sympathetic tone to the heart in both experimental protocols indicated an increased parasympathetic tone in SH mice and no changes in the sympathetic tone. Antagonism of the sympathetic tone to the vascular resistance with prazosin produced similar changes in arterial pressure in control and SH mice. Altogether these findings support the concept that mice submitted to SH present a significant increase in the parasympathetic but not in the sympathetic tone, which may explain why the baseline arterial pressure was not increased in SH mice.

Identifying phenotypic and physiological subgroups of preschoolers with autism spectrum disorder.

To understand the emergence of symptoms in autism spectrum disorder (ASD), we need to identify the mechanisms that underpin the development of core social skills. Mounting evidence indicates that young children with later ASD attend less to other people, which could compromise learning opportunities with cascading effects. Passive looking behaviour does not tell us about engagement with visual information, but measures of physiological arousal can provide information on the depth of engagement. In the current study, we use heart rate (HR) and heart rate variability (HRV) to measure engagement with social dynamic stimuli in ASD. Sixty-seven preschoolers with ASD and 65 typical developing preschoolers between 2 and 4 years of age participated in a study where HR was measured during viewing of social and non-social videos. Using latent profile analyses, more homogeneous subgroups of children were created based on phenotype and physiology. Preschool-aged children with ASD, regardless of their non-verbal, verbal and social competencies, do not differ in overall HR or HRV compared to TD children. However, the ASD group showed a larger increase in HR (more disengagement) than the TD group to later-presented social stimuli. Phenotypic and physiological profiles showed this was primarily the case for children with below average verbal and non-verbal skills, but not necessarily those with more ASD symptoms. Children with ASD, especially a subgroup showing moderate cognitive delays, show an increase in HR to social stimuli over time; this may reflect difficulties re-engaging with social information when attention is waning.

Comparison of the Active Sitting Test and Head-Up Tilt Test for Diagnosis of Postural Tachycardia Syndrome in Children and Adolescents.

Objectives: We aimed to compare the hemodynamic responses to the active sitting test with the passive head-up tilt test (HUTT) in children and adolescents with postural tachycardia syndrome (POTS). We hypothesized that sitting tachycardia was also present in POTS patients during sitting.Materials and methods: We tested 30 POTS patients and 31 control subjects (mean age = 12 years, range = 9–16 years) who underwent both active sitting test and HUTT successively. We measured the heart rate (HR) and blood pressure (BP) during each test.Results: For both POTS patients and control subjects, the HUTT produced significantly larger HR and BP increases from 3 to 10 min of postural change than did the sitting test. Moreover, POTS patients with excessive orthostatic tachycardia during the HUTT also had significantly larger increases in HR at all test intervals during the sitting test than did the control subjects. A maximum increase in HR ≥ 22 bpm within 10 min of the sitting test was likely suggested to predict orthostatic tachycardia, yielding a sensitivity and specificity of 83.3 and 83.9%, respectively. Only six of 30 POTS patients (20%) reached the 40-bpm criterion during the sitting test, and no one complained of sitting intolerance symptoms.Conclusions: We have shown that POTS patients also have sitting tachycardia when changing from a supine position to a sitting position. We believe that the active sitting test is a reasonable alternative maneuver in assessing POTS in population groups that cannot tolerate the standing test or HUTT.

Heart rate as a marker of relapse during withdrawal of heart failure therapy in patients with recovered dilated cardiomyopathy: an analysis from TRED-HF

Abstract Introduction In TRED-HF, 40% of patients with recovered dilated cardiomyopathy (DCM) relapsed in the short-term during phased withdrawal of drug therapy. Non-invasive markers of relapse may be used to monitor patients who wish a trial of therapy withdrawal and provide insights into the pathophysiological drivers of relapse. Purpose To investigate the relationship between changes in heart rate (HR) and relapse amongst patients with recovered DCM undergoing therapy withdrawal in TRED-HF. Methods Patients with recovered DCM were randomised to phased withdrawal of therapy or to continue therapy for 6 months. After 6 months of continued therapy, those in the control arm underwent withdrawal of therapy in a single arm crossover phase. HR was measured at each study visit. Mean HR and 95% confidence intervals (CI) were calculated at baseline, 45 days after baseline, 45 days prior to the end of the study or relapse and at the end of the study or relapse. Patients were stratified by treatment arm and the occurrence of the primary relapse end-point. Heart rate at follow-up was compared amongst patients who had therapy withdrawn and relapsed versus those who had therapy withdrawn and did not. ANCOVA was used to adjust for differences in HR at baseline between the two groups. Results Of 51 patients randomised, 26 were assigned to continue therapy and 25 to withdraw therapy. In the randomised and cross-over phases, 20 patients met the primary relapse end-point; one patient withdrew from the study and one patient completed follow-up in the control arm but did not enter the cross-over phase. Mean HR (standard deviation) at baseline and follow-up for (i) patients in the control arm was 69.9 (9.8) & 65.9 (9.1) respectively; (ii) for those who had therapy withdrawn and did not relapse was 64.6 (10.7) & 74.7 (10.4) respectively; and (iii) for those who had therapy withdrawn and relapsed was 68.3 (11.3) & 86.1 (11.8) respectively [all beats per minute]. The mean change in HR between the penultimate visit and the final visit for those who had therapy withdrawn and did not relapse was −2.4 (9.7) compared to 3.1 (15.5) for those who relapsed. After adjusting for differences in HR at baseline, the mean difference in HR measured at follow-up between patients who underwent therapy withdrawal and did, and did not relapse was 10.4bpm (95% CI 4.0–16.8; p=0.002) (Figure 1 & Table 1). Conclusion(s) A larger increase in HR may be a simple and effective marker of relapse for patients with recovered DCM who have insisted on a trial of therapy withdrawal. Whether HR control is crucial to the maintenance of remission amongst patients with improved cardiac function, or is simply a marker of deteriorating cardiac function, warrants further investigation. Funding Acknowledgement Type of funding source: Public grant(s) – National budget only. Main funding source(s): British Heart Foundation

Left Ventricular end Diastolic Diameter in Patients of Mild and Severe Postural Orthostatic Tachycardia Syndrome

Introduction Postural orthostatic tachycardia syndrome (POTS) is a form of dysautonomia presenting with palpitations, lightheadedness, brain fog, headaches, nausea and fainting¹. Several tests are used in POTS workup. Most important is the Tilt Table Test. POTS is diagnosed as change of 30 beats per minute(bpm) or more in adults and 40 bpm in people less than 18 or heart rate greater than 120 bpm within 10 minutes of head-up tilt table test. Left ventricular end diastolic diameter(LVEDD) shows the amount of blood in the left ventricle at the end of the diastole². If this diameter is less than normal then it may be the one reason contributing to the large increase in heart rate in severe POTS patients.The aim of the study is to indicate the role of LVEDD in increase of heart rate in patients of severe POTS as compared to mild POTS. Methods We analysed the POTS patients retrospectively. Inclusion Criteria POTS patients who underwent tilt table test during their workup, were analysed. Experimental Group Those having a change of 50 bpm or greater in heart rate during tilt table test were included in this group and termed as severe POTS patients. Total 132 patients meet this criteria. Control Group It comprises 144 patients having heart rate changes between 30 to 50 during tilt table test and termed as patients with mild POTS. LVEDD of these patients were measured through their echocardiograms. Females having LVEDD < 3.8 cm and Males having LVEDD < 4.2 cm were considered abnormally low diameter. Results Out of 132 patients of the experimental group (severe POTS), 32 patients (24%) had below normal LVEDD i.e. below 3.8 cm in females and below 4.2 cm in males. While in the control group, 36 patients (25%) out of 144 had abnormal LVEDD. Remaining patients have their LVEDD within the normal range. Postural orthostatic tachycardia syndrome (POTS) is a form of dysautonomia presenting with palpitations, lightheadedness, brain fog, headaches, nausea and fainting¹. Several tests are used in POTS workup. Most important is the Tilt Table Test. POTS is diagnosed as change of 30 beats per minute(bpm) or more in adults and 40 bpm in people less than 18 or heart rate greater than 120 bpm within 10 minutes of head-up tilt table test. Left ventricular end diastolic diameter(LVEDD) shows the amount of blood in the left ventricle at the end of the diastole². If this diameter is less than normal then it may be the one reason contributing to the large increase in heart rate in severe POTS patients.The aim of the study is to indicate the role of LVEDD in increase of heart rate in patients of severe POTS as compared to mild POTS. We analysed the POTS patients retrospectively. POTS patients who underwent tilt table test during their workup, were analysed. Those having a change of 50 bpm or greater in heart rate during tilt table test were included in this group and termed as severe POTS patients. Total 132 patients meet this criteria. It comprises 144 patients having heart rate changes between 30 to 50 during tilt table test and termed as patients with mild POTS. LVEDD of these patients were measured through their echocardiograms. Females having LVEDD < 3.8 cm and Males having LVEDD < 4.2 cm were considered abnormally low diameter. Out of 132 patients of the experimental group (severe POTS), 32 patients (24%) had below normal LVEDD i.e. below 3.8 cm in females and below 4.2 cm in males. While in the control group, 36 patients (25%) out of 144 had abnormal LVEDD. Remaining patients have their LVEDD within the normal range.

Heart rate and skin conductance responses to taste, taste novelty, and the (dis)confirmation of expectations

It is unclear whether the responses of the autonomic nervous system (ANS) can measure how people respond to food. Results focused on emotional responses are contradictory; therefore, the focus has shifted to other components of emotion, such as appraisals. The aim of this study was, therefore, to evaluate the differences in ANS responses related to appraisals; particularly taste novelty, valence, and the disconfirmation of expectations.A hundred and fifty-five participants joined this study. They tasted samples of different valence (sweet and bitter) twice: the first time without knowing the taste and the second while being informed of the taste. After this first block, participants tasted two additional samples: one that confirmed expectations and one that disconfirmed them. Heart rate and skin conductance were measured. Results show that the second experience with a taste led to cardiac deceleration. Heart rate changes were only related to valence when participants’ expectations were (dis)confirmed. Heart rate decreased for those tastes that disconfirmed expectations and increased for those that confirmed them and the sweet sample had larger increases in heart rate than the bitter. Skin conductance changed in regards to novelty and valence but not to the disconfirmation of expectations. It increased for the bitter sample, decreased for the sweet, and was always higher during the first experience than during the second. In conclusion, the results suggest that cardiac responses are more sensitive to novelty and the disconfirmation of expectations while skin conductance responses capture novelty and valence.

Patterns of brain and cardiovascular activation while solving rule-discovery and rule-application numeric tasks

It is known that solving mental tasks leads to tonic increase in cardiovascular activity. Our previous research showed that tasks involving rule application (RA) caused greater tonic increase in cardiovascular activity than tasks requiring rule discovery (RD). However, it is not clear what brain mechanisms are responsible for this difference. The aim of two experimental studies was to compare the patterns of brain and cardiovascular activity while both RD and the RA numeric tasks were being solved. The fMRI study revealed greater brain activation while solving RD tasks than while solving RA tasks. In particular, RD tasks evoked greater activation of the left inferior frontal gyrus and selected areas in the parietal, and temporal cortices, including the precuneus, supramarginal gyrus, angular gyrus, inferior parietal lobule, and the superior temporal gyrus, and the cingulate cortex. In addition, RA tasks caused larger increases in HR than RD tasks. The second study, carried out in a cardiovascular laboratory, showed greater increases in heart rate (HR), systolic blood pressure (SBP), diastolic blood pressure (DBP), and mean arterial pressure (MAP) while solving RA tasks than while solving RD tasks. The results support the hypothesis that RD and RA tasks involve different modes of information processing, but the neuronal mechanism responsible for the observed greater cardiovascular response to RA tasks than to RD tasks is not completely clear.

Postural Heart Rate Changes in Young Patients With Vasovagal Syncope.

Recurrent postural vasovagal syncope (VVS) is caused by transient cerebral hypoperfusion from episodic hypotension and bradycardia; diagnosis is made by medical history. VVS contrasts with postural tachycardia syndrome (POTS), defined by chronic daily symptoms of orthostatic intolerance with excessive upright tachycardia without hypotension. POTS has recently been conflated with VVS when excessive tachycardia is succeeded by hypotension during tilt testing. We hypothesize that excessive tachycardia preceding hypotension and bradycardia is part of the vasovagal response during tilt testing of patients with VVS. We prospectively performed head-up tilt (HUT) testing on patients with recurrent VVS (n = 47, 17.9 ± 1.1 y), who fainted at least 3 times within the last year, and control subjects (n = 15, 17.1 ± 1.0 y), from age and BMI-matched volunteers and measured blood pressure, heart rate (HR), cardiac output, total peripheral resistance, and end tidal carbon dioxide. Baseline parameters were the same in both groups. HR (supine versus 5 and 10 minutes HUT) significantly increased in control (65 ± 2.6 vs 83 ± 3.6 vs 85 ± 3.7, P < .001) and patients with VVS (69 ± 1.6 vs 103 ± 2.3 vs 109 ± 2.4, P < .001). HUT in controls maximally increased HR by 20.3 ± 2.9 beats per minute; the increase in patients with VVS of 39.8 ± 2.1 beats per minute was significantly greater (P < .001). An increase in HR of ≥40 beats per minute by 5 and 10 minutes or before faint with HUT, occurred in 26% and 44% of patients with VVS, respectively, but not in controls. Orthostasis in VVS is accompanied by large increases in HR that should not be construed as POTS.

Hyperthermia and supraspinal fatigue.

Hyperthermia and supraspinal fatigue.

Hierarchy and health: Physiological effects of interpersonal experiences associated with socioeconomic position.

The inverse association between socioeconomic position (SEP) and cardiovascular disease may involve social psychophysiological processes. To test effects of aspects of SEP on physiological reactivity, we experimentally manipulated 3 features of social context related to social hierarchy-social rank or status relative to an interaction partner, the partner's degree of dominant behavior, and the presence of social-evaluative threat. The study design was a 2 × 2 × 2 × 2 (Participant Relative Status [high vs. low] × Partner Dominance [high vs. low] × Evaluative Threat [high vs. low] × Sex [male vs. female]) factorial, and 180 undergraduates participated. Cardiovascular and salivary cortisol responses were measured while participants engaged in a controlled interaction task with a prerecorded confederate partner. Lower participant relative status resulted in greater increases in systolic (SBP) and diastolic blood pressure (DBP). Interacting with a more dominant partner resulted in greater increases in SBP and heart rate (HR), and larger changes in cardiac sympathetic and parasympathetic activation. Higher levels of social-evaluative threat evoked larger increases in HR and SBP. In some cases, these effects were stronger in men than in women, and aspects of the low status social context had synergistic effects on some physiological outcomes. Interpersonal interactions and experiences may contribute to the association between SEP and cardiovascular health through the mechanism of physiological activation. Recurring patterns of everyday social experiences and their physiological effects may be a pathway linking the broader social context to cardiovascular disease. (PsycINFO Database Record

Dehydration Enhances Pain-Evoked Activation in the Human Brain Compared with Rehydration

Negative effects of dehydration on the human brain and cognitive function have been reported. In this study, we examined the effects of dehydration on pain thresholds and cortical activations in response to pain, compared with rehydration with an oral rehydration solution (ORS) by functional magnetic resonance imaging. Five healthy adult men were subjected to dehydration and rehydration on 2 different days. The condition on the first day was randomly assigned to each subject. They completed a 40-minute exercise protocol using a walking machine after 12 hours of fasting under both conditions. For rehydration, the subjects consumed up to 3000 mL ORS starting from the night before the test day. After exercise, a painful stimulus (cold pressor test) was applied to the subjects' medial forearm in a magnetic resonance imaging scanning gantry, and pain-evoked brain activation was analyzed. On the rehydration day, each of the subjects consumed an average of 2040 mL (range; 1800-2500 mL) ORS. Physiological data revealed that subjects when dehydrated lost more weight from exercise than subjects when rehydrated had a larger heart rate increase, a higher tympanic temperature, and a higher urine osmolality. Subjective data revealed that the subjects reported significantly stronger thirst while dehydrated than while rehydrated with ORS, although the levels of hunger and anxiety and mood did not significantly differ between conditions. The cold pressor test robustly activated the pain-related neural network, notably the anterior cingulate cortex, insula, and thalamus. Such activations in the dehydrated subjects were greater than those in the rehydrated subjects in terms of peak and cluster, accompanied by a decrease in pain threshold (P = 0.001). Our findings suggest that dehydration brings about increased brain activity related to painful stimuli together with enhanced thirst, whereas rehydration with ORS alleviates thirst and decreases brain activity related to painful stimuli.

Effect of synthetic colloid administration on hemodynamic and laboratory variables in healthy dogs and dogs with systemic inflammation.

To compare the effects of administering equal volumes of isotonic crystalloids and synthetic colloids on hemodynamic and laboratory variables in healthy dogs and dogs with systemic inflammation. Randomized, placebo-controlled, blinded study. Comparative clinical research facility. Sixteen adult purpose-bred Beagles. Dogs were first randomized to receive either lipopolysaccharide (LPS; 5 μg/kg, IV) or an equal volume of placebo (0.9% NaCl, IV). Dogs were then randomized into 1 of 2 groups receiving fluid resuscitation with either 40 mL/kg IV isotonic crystalloid (0.9% NaCl) or synthetic colloid (tetrastarch). After a 14-day washout, the study was repeated such that dogs received the opposite treatment (LPS or placebo) and the same resuscitation fluid regimen. Vital signs (heart rate (HR), oscillometric blood pressure) were measured and blood samples were collected for PCV, total plasma protein (TPP), serum lactate concentration, and colloid osmotic pressure (COP) measurements. Healthy (placebo) dogs had similar decreases in PCV and TPP after administration of either fluid. Tetrastarch administration was associated with a larger increase in HR, systolic blood pressure, and mean blood pressure. Dogs with systemic inflammation had similar increases in systolic blood pressure and decreases in PCV, TPP, and lactate after administration of either fluid. Tetrastarch administration caused greater immediate increase in HR and mean blood pressure compared to 0.9% NaCl. In all dogs, 0.9% NaCl administration decreased COP and tetrastarch administration increased COP. Resuscitation with equal volumes of 0.9% NaCl and tetrastarch caused similar changes in hemodynamic and laboratory variables in dogs with LPS-induced systemic inflammation; however, larger increases in HR and blood pressure were seen within the first 2 hours following tetrastarch administration compared to 0.9% NaCl. Tetrastarch administration increased COP in all dogs, despite a decrease in TPP.

Physiological Reactivity to Infant Crying and Observed Maternal Sensitivity

Relations between maternal sensitivity and physiological reactivity to infant crying were examined using measures of heart rate (HR) and respiratory sinus arrhythmia (RSA) in 49 mothers of second‐born infants. Using the Ainsworth Sensitivity Scale, an independent assessment of maternal sensitivity was made during maternal free play and bathing of their infants. Physiological reactivity was measured while mothers listened to three blocks of infant cry sounds in a standard cry paradigm. Mothers scoring high on sensitivity were compared to less sensitive mothers on both their physiological reactivity to the presented crying sounds and their physiological mean‐level differences. Significant interaction effects were found for both HR and RSA. Highly sensitive mothers showed a larger increase in HR and stronger RSA withdrawal in response to the first block of cry sounds compared to less sensitive mothers. Main effects showed that highly sensitive mothers had lower mean overall HR, and higher mean RSA levels across all three blocks of crying sounds compared to less sensitive mothers. RSA withdrawal and accompanying HR increases are discussed from a polyvagal perspective as indicative of a better capability in responding to infant signals of negative affect.

Prior Peritraumatic Dissociative Experiences Affect Autonomic Reactivity During Trauma Recall

To better understand the psychophysiological correlates of peritraumatic dissociation (PD), the present study examined the relationship between reports of prior PD and sympathetic and parasympathetic functioning in response to a laboratory stress paradigm in 39 traumatized female undergraduates. Participants were asked to talk about their most distressing traumatizing experience while continuous measures of heart rate, pre-ejection period, and respiratory sinus arrhythmia were taken. Overall, high dissociators had significantly larger increases in heart rate and larger decreases in pre-ejection period and respiratory sinus arrhythmia during trauma recall. In opposition to our hypothesis, these results suggest that female trauma victims reporting high levels of PD during a prior trauma may be more reactive to traumatic reminders than victims who report lower levels of PD.

The Effects of Realistic Reward and Risk on Simulated Gambling Behavior

Laboratory studies on gambling may not represent an accurate analog of actual gambling behavior because they typically fail to model a meaningful level of risk and reward that is given in real-world settings. The current study sought to address this problem. One hundred and twenty college students were given the opportunity to bet valued experimental credits required for passing an introductory psychology course on the outcome of a videotaped horse race while their heart rate was monitored. Of those, 67 decided to wager, whereas 53 did not. Individuals who wagered course credits demonstrated a larger increase in heart rate and reported more subjective excitement during the race compared to individuals who did not bet. While the bettors' heart rates remained elevated after the end of the race, reports of subjective excitement depended on whether individuals had won or lost their wager. Significant gender differences and differences in personality were also found between the groups of bettors and nonbettors. These findings demonstrate that arousal in response to gambling is related to the potential for both risk and reward.